1. Field of the Invention
The present invention relates generally to a chassis dynamometer for testing performance of a tested object. More specifically, the present invention relates to a twin roller type chassis dynamometer having a load roller drivingly connected to a dynamometer and a free roller, wherein a flywheel serving as an inertial load for a tested object is rotated faster than the load and free rollers.
2. Description of the Background Art
Chassis dynamometers have been used for testing performance of, for example, automotive vehicles including output and fuel consumption characteristics by simulating an actual road test, for example, by simulating running resistance, up-and down-hill road, vehicular load and the like. Accordingly, in order to obtain a precise result of the test, various conditions for the test should be set or controlled properly.
One of the conditions to be properly controlled is a simulation of an inertial load caused by a vehicle weight. In order to simulate the vehicular inertial mass, a flywheel is used which is connected to a roller of the chassis dynamometer.
In one type using the flywheel as the vehicular inertial mass, a tested vehicular wheel is placed on a roller to be driven by the vehicular wheel. The roller is drivingly connected to the dynamometer for measuring the performance of the vehicle. The roller is further connected to the flywheel for co-rotation therewith so as to provide the simulated vehicular inertial load. The flywheel is typically provided outside the roller.
On the other hand, another type, i.e. a twin roller type chassis dynamometer has been proposed in which a pair of rollers are used. Specifically, one roller (hereinafter referred to as "load roller") is drivingly connected to the dynamometer and the other roller (hereinafter referred to as "free roller") is connected to the flywheel for co-rotation therewith. The tested vehicular wheel is placed between the load and free rollers so that the flywheel applies the simulated vehicular inertial load to the tested vehicular wheel. The flywheel is typically provided in the free roller.
In the foregoing twin roller type chassis dynamometer, however, since the flywheel and the free roller-co-rotate, i.e. rotate at a rotation ratio of 1:1, in order to increase the flywheel inertial load, increment of a diameter of the flywheel and/or increment of a weight of the flywheel is inevitably required. This raises a problem particularly when the flywheel is provided in the free roller. Specifically, when the flywheel of a larger diameter is used, difficulty is encountered due to limited space for mounting the flywheel in the free roller. On the other hand, when the flywheel of a larger weight is used, difficulty is encountered since reinforcement for the free roller becomes essential for avoiding possibility of distortion, vibration and creation of noise.